Kater had to cover 213 km. He has already covered 140 km. How many kilometers less was he left to walk than he was?

The sought unknown number of kilometers, which the boat has covered more than it still has to go, can be expressed using the conditional variable “Y”.

Then, taking into account the information of this problem, we get the following equation: Y = 140 – (213 – 140).

The result of solving the existing equation looks like this Y = 140 – 73 = 67 kilometers.

Answer: 67 kilometers.